Base version copied from: https://github.com/emilybache/GildedRose-Refactoring-Kata/tree/main
This is my attempt at handling the kata.
I wouldn't argue it's perfect but it's in my opinion a good balance of improvement vs time spent/changes made.
Some more elaborated patterns and solutions could be used but it feel premature at this stage. If more expansion require more refactoring having a set of scpecs should help even if the person making the following change don't have access to the initial rules of previous items (as is often the case).
Sulfuras handling could be argued i chose the approach of making it invariable instead of refixing it to an arbitrary value.